Error establishing a database connection on subdomains using Multi-db

Hi Guys,

I've setup multi database plugins.
Everything is fine on the main blog, but I get "Error establishing a database connection" on all the subdomains.
I've created all the databases, assigned the users to the databases, edited the files and uploaded them to the server. All the tables are in the new databases.

Could you please help?

Thanks!
Razvan